Dietary polyphenols and the risk of colorectal cancer in the prospective Southern Community Cohort Study.

backgroundPolyphenols are antioxidants with promising anticancer properties, but few studies have examined the associations of specific dietary polyphenols with colorectal cancer (CRC) risks or among Black individuals in the United States.

objectivesWe examined the associations between dietary polyphenols and CRC and assessed differences in these associations or polyphenol intakes by subgroups, including race (Black and White), that may contribute to cancer disparities.

methodsThe Southern Community Cohort Study prospectively enrolled individuals from the southeastern United States during 2002-2009, most of whom had a low income or are Black. Validated FFQ data and polyphenol databases were used to estimate polyphenol intakes. Cox proportional hazards models were used to obtain HRs and 95% CIs for the highest compared to the lowest intake quintiles (Qs) of specific polyphenols. Median intakes of quintiles were used to obtain linear trends, and restricted cubic splines were used to obtain nonlinear trends. Subgroup analyses were conducted by cancer site, sex, race, household income, and BMI-defined obesity status.

resultsAmong 71,599 participants, the median polyphenol intake was lower for Black individuals (452 mg/day; IQR, 277-672 mg/day) than White individuals (958 mg/day; IQR, 587-1597 mg/day). A significant, inverse, nonlinear association was observed for total polyphenol intake with the CRC risk (HR, 0.57; 95% CI, 0.38-0.86; P = 0.008 comparing 650 mg/day of intake to 0 mg/day). In addition, inverse linear associations were observed for tyrosols and the CRC risk (HRQ5vsQ1, 0.68; 95% CI, 0.50-0.91; P = 0.0014) and for hydroxybenzoic acids and the rectal cancer risk (HRQ5vsQ1, 0.49; 95% CI, 0.29-0.82; P = 0.0007). Associations were consistent by sex, race, income, and BMI.

conclusionsIncreasing intakes of total polyphenols, tyrosols, and hydroxybenzoic acids were associated with decreased CRC or rectal cancer risks, and associations were consistent across subgroups. Differences in polyphenol intakes may contribute to the increased CRC incidence among Black US individuals.